Arca Budgie Sony A7-series Shift-and-Stitch Adapter 20230505

Use your full-frame Sony E-mount (FE) body to capture images up to 48x36mm -- generously larger than the 44x33mm sensors people are often calling medium format. I argue that's really best considered as multi-aspect 135 film (35mm) format for getting the largest possible coverage sampling using a designed-for-full-frame lens.

Budgie is an adapter for Leica M to Sony FE -- except it does offset shifting and, unlike the original version, includes an Arca-Swiss compatible mount as well as 1/4-20 threaded mounting holes. The Budgie name comes from the idea that the camera can be budged +/-12mm relative to the mounted lens to capture multiple images for stitching. Use of M mount allows most old manual lens mounts to be used by adding an adapter to M mount.

This 20230505 version has two major improvements:

• The earlier versions of Budgie had a thicker wall on the FE-mount part.  This version thins the thickness of the FE-mount walls to the bare minimum that still appears to be structurally sound -- making the clear central region 4mm larger and chamfering the edges for 1mm as well. This was done because the width of the FE-mount itself is a potential cause for vignetting, so a thinner wall might vignette less. Apparently, for some lenses it does make a difference...
• Notice that the top edge of Budgie is now changed so that there is more clearance with the body grip and it is much easier to press the FE-mount release button with Budgie mounted. Earlier versions were particularly difficult to remove once mounted because Budgie partly extended over the release button. This change was made possible by replacing the relatively heavy follower pin at the top with a smaller sliding track. In theory, the new design is weaker, but it doesn't yet seem to be a problem. The new design does require a bit of more precise welding in assembly.

The new version also has a two-color printable body version too, saving the annoyance of having to paint the raised logo, but it still works as a single-color print.

Basically, you print 1 each of:

• budgie20230505methin.stl
• budgie20230505mm
• budgie20230505mw
• budgie20230505ms
• budgie20230505screw

The mw and ms parts need to get welded to the methin part (e.g., using a soldering iron). The mm part can instead be replaced by the mmmain and mmlogo parts for a two-color print. The screw is used as a set screw to lock the M lens or adapter in place, screwing in from the FE-mount side. The set screw is deliberately undersized to make it easier to thread, and it also would not hurt to run a ¼-20 screw through the threaded hole in the mm part to ensure the thread is clean before screwing-in the 3D-printed set screw.

As a simple example of what to expect, there is an 84MP image stitched from three shots using Budgie with a Minolta MD 28mm f/2.8 lens @ f/11 on a 42MP Sony A7RII. Not all full-frame lenses will cover 48x36mm as well, but most will still produce an image at least comparable to the 44x33mm sensor commonly used in “medium format” cameras.